1. Field of Invention
The invention relates to a transfer assist apparatus and a control method for the transfer assist apparatus. In particular, the invention relates to a transfer assist apparatus that has an arm structure, and a control method for the transfer assist apparatus.
2. Description of Related Art
For a care recipient who has difficulty in walking without a help, it is not easy to carry out the movement of a transfer, such as a transfer from a bed to a wheelchair, or the like, by him/herself without a help. Therefore, such a care recipient usually needs a help from a care giver. However, the helping in the transfer involves a considerable physical burden on the care giver, and places a considerable mental burden on the care recipient as well. Therefore, in recent years, many transfer assist apparatuses that assist a person having difficulty in self-helped walking in the transfer motion have been developed.
Japanese Patent Application Publication No. 2008-073501 (JP-A-2008-073501) discloses a transfer assist apparatus which has an arm structure that includes a plurality of links (joints), and in which a distal end portion of the arm structure is provided with a holder device for holding a care recipient. Usually, such a transfer assist apparatus is able to freely control the posture of the holder device by controlling the angles of the joints, and the like.
However, if the degree of freedom in the control of the posture of the holder device increases, there occurs a possibility that the posture of the holder device may become a posture that causes the care-receiving person to have a pain, due to the care giver making an error in operating the transfer assist apparatus. On the other hand, if a care giver operates the apparatus very carefully in order to avoid the foregoing problem, there arises a possibility of the operation taking a considerable amount of time.